1. Technical Field
The present invention relates to a liquid ejecting head and a liquid ejecting apparatus, each including a pressure generating chamber communicating with a nozzle aperture and a piezoelectric element that includes a piezoelectric layer and electrodes applying a voltage to the piezoelectric layer and functions to change the pressure in the pressure generating chamber, and relates to the piezoelectric element.
2. Related Art
Some of the piezoelectric elements used in liquid ejecting heads have a structure in which a piezoelectric layer made of a piezoelectric material capable of electromechanical conversion, such as a crystallized dielectric material, is disposed between two electrodes. This type of piezoelectric element can be used as a deflection vibration mode actuator device in a liquid ejecting head. Ink jet recording heads are a typical type of liquid ejecting head. An ink jet recording head includes a vibration plate defining a part of a pressure generating chamber communicating with nozzle apertures through which ink droplets are ejected. In the ink jet recording head, a piezoelectric element deforms the vibration plate to apply a pressure to the ink in the pressure generating chamber, thereby ejecting ink droplets through the nozzle apertures.
The piezoelectric ceramic film of the piezoelectric element is required to have high piezoelectric properties, and a typical example of the piezoelectric material is lead zirconate titanate (PZT) (see JP-A-2001-223404). However, lead zirconate titanate contains lead. From the viewpoint of environmental protection, lead-free piezoelectric materials are desired. Accordingly, piezoelectric materials have been developed which do not contain lead, but have piezoelectric properties equal to PZT. For example, piezoelectric materials having a bismuth ferrate (BiFeO3)-based perovskite structure containing bismuth and iron have been proposed. For example, JP-A-2009-252789 discloses a complex oxide expressed as a mixed crystal of bismuth ferrate manganate such as Bi(Fe, Mn)O3 and barium titanate such as BaTiO3.
However, bismuth ferrate-based piezoelectric materials are liable to crack during the production and after a certain time has elapsed from the production.
This issue arises not only in ink jet recording heads, but also in other liquid ejecting heads that eject droplets other than ink, and piezoelectric elements used for applications other than liquid ejecting heads have the same issue.